-er -ol bbb bbc bbe bbk bbl bbo bbr bcb bcc bce bck bcl bco bcr be- beb bec bee bek bel beo ber bkb bkc bke bkk bkl bko bkr blb blc ble blk bll blo blr bob boc boe bok bol boo bor brb bre brk brl bro brr c-- cbb cbc cbe cbk cbl cbo cbr ccb ccc cce cck ccl cco ccr ce- ceb cec cee cek cel ceo cer ckb ckc cko cl- clb clc cle clk cll clo clr co- cob coc coe cok col coo cor crb crc cre crk crl cro crr ebb ebc ebe ebk ebl ebo ebr ec- ecb ecc ece eck ecl eco ecr eeb eec eee eek eel eeo eer ekb ekc eke ekl eko ekr elb elc ele elk ell elo elr eo- eob eoc eoe eok eol eoo eor erb erc ere erk erl ero err kbb kbc kbe kbk kbl kbo kbr kcb kcc kce kck kcl kcr ke- keb kec kee kek kel keo ker kkb kkc kke kkk kkl kkr kl- klb klc klo klr kob koc koe kok kol koo kor krc krk krl kro krr lbb lbc lbe lbk lbl lbo lbr lcb lcc lce lck lcl lco lcr leb lec lee lek lel leo ler lkb lkl lkr llb llc lle llk lll llo llr lob loc loe lok lol loo lor lrb lrc lrk lro lrr ob- obb obc obe obk obl obo obr oc- ocb occ ock ocl oco ocr oeb oec oee oel oeo oer okb okc oke okk okl oko okr olb olc ole olk oll olo oo- oob ooc ook ool ooo oor or- orb orc ore ork orl oro orr rbb rbc rbe rbk rbl rbo rbr rcb rcc rce rcl rco rcr re- reb rec ree rek rel reo rer rkb rkc rke rkk rko rlc rle rll rlo rlr rob roc roe rok rol roo ror rrb rrc rrk rrl rrr